JPH0580558A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body having high sensitivity and excellent durability by forming a photosensitive layer contg. a specified azo compd. on an electric conductive substrate. CONSTITUTION:A photosensitive layer contg. an azo compd. represented by the formula (where A is the residue of a coupler) is formed on an electric conductive substrate. The azo compd. represented by the formula has high sensitivity and can prevent the lowering of surface potential due to repeated use because the structure of m-terphenyl known as a quenching agent has been introduced into the molecule. The azo compd. can stably maintain high sensitivity to exposure for a long time or at a high temp. and has excellent light stability. The resulting electrophotographic sensitive body with the photosensitive layer contg. the azo compd. has high sensitivity and excellent durability.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrophotographic photoreceptor,
More specifically, the present invention relates to an electrophotographic photosensitive member used in an electrostatic copying machine, a laser beam printer or the like.

[0002]

2. Description of the Related Art The Carlson process is widely used to form a copied image using an electrophotographic photosensitive member. The Carlson process consists of a charging process that uniformly charges the photoconductor by corona discharge, an exposure process that exposes the document image on the charged photoconductor to form an electrostatic latent image corresponding to the document image, and an electrostatic latent image. A developing step of developing with a developer containing toner to form a toner image, a transfer step of transferring the toner image to a base material such as paper, a fixing step of fixing the toner image transferred to the base material, and a transfer step. After the step, a cleaning step of removing the toner remaining on the photoconductor is included.

In order to form a high quality image in the Carlson process, the electrophotographic photosensitive member is required to have excellent charging characteristics and photosensitive characteristics and to have a low residual potential after exposure. Conventionally, inorganic photoconductors such as selenium and cadmium sulfide have been known as electrophotographic photosensitive materials, but they are toxic and are not desirable because of high production cost.

Therefore, in place of these inorganic substances, so-called organic electrophotographic photoreceptors using various organic substances which are excellent in processability and advantageous in terms of manufacturing cost and have a high degree of freedom in functional design. Is proposed. Such an organic electrophotographic photosensitive member usually has a photosensitive layer composed of a charge generating material that generates an electric charge upon exposure and a charge transporting material that has a function of transferring the generated electric charge.

In order to satisfy various conditions desired for such an organic electrophotographic photosensitive member, it is necessary to appropriately select these charge generating material and charge transporting material. As the charge generating material, many compounds such as phthalocyanine compounds, perylene compounds, quinacridone compounds, ansanthrone compounds, azo compounds have been proposed. For example, as azo compounds, those disclosed in JP-A-47-37543 and JP-A-57-195767 are known.

[0006]

However, the above-mentioned conventional charge generating materials have the problems that the photosensitive wavelength region is narrow, the sensitivity is low, or the photostability is insufficient. The photoconductor containing the generating material was also inferior in sensitivity and durability. The present invention solves the above problems, and an object of the present invention is to provide an electrophotographic photoreceptor having excellent characteristics such as high sensitivity and excellent durability.

[0007]

The electrophotographic photosensitive member of the present invention for solving the above problems contains an azo compound represented by the following general formula (I) on a conductive substrate. It is characterized in that a photosensitive layer is provided.

[0008]

[Chemical 2]

[In the formula, A represents a coupler residue] According to the studies by the present inventors, the azo compound represented by the above general formula (I) is known as a quencher in the molecule. Since the structure of -terphenyl is introduced, it has high sensitivity and can prevent a decrease in surface potential due to repeated use. Furthermore, it is possible to stably maintain a high sensitivity to long-time exposure or exposure at high temperature, and it is excellent in light stability. Therefore, the electrophotographic photosensitive member of the present invention having the photosensitive layer containing the azo compound has high sensitivity and excellent durability.

The reasons why the above-mentioned azo compounds have such high sensitivity and photostability are considered as follows. That is, the azo compound represented by the above general formula (I) can be obtained, for example, from the above-mentioned JP-A-47-37.
No. 543, the following general formula (III):

[0011]

[Chemical 3]

A conventional bisazo system represented by the formula [A represents the same coupler residue as described above and Y represents a hydrogen atom, a methyl group, a methoxy group, an ethoxy group, a hydroxyl group, a chlorine atom or a bromine atom] Compared to compounds and the like, the π-electron conjugated system formed by the m-terphenyl moiety and two azo groups has a larger spread, and thus planarization of the molecular structure of the compound is further promoted, It is presumed that this is because intermolecular interaction due to overlap between molecules is strengthened.

The azo compound represented by the above general formula (I) basically contains a bisazo compound represented by the following general formula (Ia).

[0014]

[Chemical 4]

[Wherein A represents the same coupler residue as described above] In the azo compound represented by the general formula (I), the coupler residue A is represented by the following general formulas (a) to (g).
The group represented by is exemplified.

[0016]

[Chemical 5]

In each formula, R ⁴ is a hydroxyl group, a group represented by the following general formula: —NR ¹⁰ R ¹¹ (wherein R ¹⁰ and R ¹¹ are the same or different and each represents a hydrogen atom or an alkyl group). Or a group represented by the following general formula: —NHSO ₂ R ¹² (in the formula, R ¹² represents a hydrogen atom, an alkyl group, an alkenyl group or an aryl group).

R ⁵ represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a carboxyl group, an alkoxycarbonyl group, a carbamoyl group, an aryl group or a sulfamoyl group, and the alkyl group or the alkoxy group is a halogen atom, a phenyl group, It may have a substituent such as a naphthyl group, a nitro group and a cyano group. In addition, the carbamoyl group or the sulfamoyl group may have a substituent such as a halogen atom, a phenyl group, a naphthyl group, an alkyl group, an alkenyl group, a carbonyl group or a carboxyl group.

R ⁶ represents an atomic group necessary for forming an aromatic ring, an aliphatic ring or a hetero ring by being condensed with the benzene ring having R ⁴ and R ⁵ mentioned above, and these rings are the same as those described above. May have a substituent. R ⁷ represents a hydrogen atom, an amino group, an N-substituted amino group, an alkyl group, an alkenyl group, a hydroxyl group, a carbamoyl group, a carboxyl group or an alkoxycarbonyl group, and the alkyl group, the alkenyl group and the carbamoyl group are the same as defined above. May have a substituent.

R ⁸ represents a hydrogen atom, an alkyl group or an aryl group, and the alkyl group or the aryl group may have the same substituent as described above. R ⁹ represents a phenylene group or a naphthylene group. These phenylene groups or naphthylene groups may also have the same substituents as described above. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and a tert group.
A butyl group, a pentyl group, a hexyl group, etc., having 1 to 1 carbon atoms
And 6 lower alkyl groups.

As the aryl group, for example, a phenyl group,
Examples thereof include a tolyl group, a xylyl group, a biphenyl group, a naphthyl group, an anthryl group and a phenanthryl group. As the alkenyl group, for example, vinyl group, allyl group, 2-butenyl group, 3-butenyl group, 1-methylallyl group, 2-
Examples thereof include lower alkenyl groups having 2 to 6 carbon atoms such as pentenyl group and 2-hexenyl group.

Examples of the halogen atom include chlorine atom, bromine atom, iodine atom and fluorine atom. Examples of the alkoxy group include a lower alkoxy group having 1 to 6 carbon atoms in the alkoxy moiety, such as a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a pentyloxy group and a hexyloxy group. Be done.

The alkoxycarbonyl group is, for example, an alkoxy moiety such as a methoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, an isopropoxycarbonyl group, a butoxycarbonyl group, an isobutoxycarbonyl group, a pentyloxycarbonyl group and a hexyloxycarbonyl group. And a lower alkoxycarbonyl group having 1 to 6 carbon atoms.

Examples of the acyl group include formyl group, acetyl group, propionyl group, butyryl group, isobutyryl group, valeryl group, isovaleryl group and hexamoyl group. In R ⁶ , the atomic group necessary for condensing with the benzene ring having R ⁴ and R ⁵ to form an aliphatic ring includes, for example, methylene group, ethylene group, propylene group, butylene group, and the like. 1-4 alkylene groups can be mentioned.

In R ⁶ , the atomic group necessary for forming a heterocycle by condensing with a benzene ring having R ⁴ and R ⁵ is, for example, a benzofuranyl group, a benzothiophenyl group, an indolyl group, 1H- Indolyl group, bezoxazolyl group, benzothiazolyl group, 1H-indazolyl group, benzimidazolyl group, chromenyl group, chromanyl group, isochromanyl group, quinolinyl group, isoquinolinyl group, cinnolinyl group, phthalazinyl group, quinazonilyl group, quinoxalinyl group, dibenzofuranyl group, carbazolyl group Group, xanthenyl group, acridinyl group, phenanthridinyl group, phenazinyl group, phenoxazinyl group,
Examples thereof include thianthrenyl group.

The aromatic heterocyclic group formed by condensing the benzene ring having R ⁴ and R ⁵ with R ⁶ is, for example, a thienyl group, a furyl group, a pyrrolyl group, an oxazolyl group, an isoxazolyl group or a thiazolyl group. , Isothiazolyl group, imidazolyl group, pyrazolyl group, triazolyl group, tetrazolyl group, pyridyl group and thiazolyl group. Further, it may be a heterocyclic group condensed with an aromatic ring (for example, a benzofuranyl group, a benzimidazolyl group, a benzoxazolyl group, a benzothiazolyl group, a quinolyl group).

Specific examples of the coupler residue A represented by the above general formulas (a) to (g) include the following groups.

[0028]

[Chemical 6]

The azo compound of the present invention represented by the above general formula (I) can be synthesized by various methods via the diazonium salt represented by the following general formula (II) as an intermediate.

[0030]

[Chemical 7]

[Wherein X is a hydrohalic acid such as hydrochloric acid,
Indicates anions of borofluoric acid, hydrobromic acid, sulfuric acid, nitric acid, perchloric acid and other acids] For example, the above general formula (Ia)
As an example of the bisazo compound represented by the formula (1), as shown in the following reaction formula, two amino groups in the amine compound represented by the general formula (1) are diazotized to form a tetrazonium salt (IIa ) And then by coupling this with a predetermined coupler in an organic solvent, it can be easily produced.

[0032]

[Chemical 8]

[In the formula, A and X are the same as above] In the diazotization, while stirring an acidic aqueous solution of the amine compound (1),
Sodium nitrite or nitrite at low temperature (usually -10
(About 5 ° C.), and then the acid as the source of the anion X is added to obtain a crystallized tetrazonium salt (IIa). Next, a bisazo compound (Ia) is obtained by adding a predetermined amount of coupler (2) to the tetrazonium salt (IIa) in an organic solvent to cause a coupling reaction.

As the organic solvent used in the above reaction,
Examples thereof include dimethylformamide and dimethyl sulfoxide. In the electrophotographic photoreceptor of the present invention, the above-mentioned azo compound can be used alone as a charge generating material, or can be used in combination with other conventionally known charge generating materials.

Other charge generating materials include, for example, amorphous silicon, pyrylium salt, anthanthrone pigment, phthalocyanine pigment, indigo pigment, triphenylmethane pigment, slene pigment, toluidine pigment,
Examples thereof include pyrazoline pigments, perylene pigments, quinacridone pigments and the like. These charge generating materials are used alone or in combination of two or more so as to have an absorption wavelength region in a desired region.

The constitution of the present invention can be applied to both so-called single-layer type and laminated type electrophotographic photoconductors. In order to obtain a single-layer type photoreceptor, a photosensitive layer containing a charge generating material, an azo compound represented by the general formula (I), a charge transporting material, a binder resin, etc. is applied. It may be formed on the conductive base material by any means.

In order to obtain a laminated type photoreceptor, a charge generating layer containing the above-mentioned azo compound as a charge generating material is formed on a conductive substrate by means of coating or the like, and this charge generating layer is formed. A charge transport layer containing a charge transport material and a binder resin may be formed thereover. On the contrary to the above, a charge transport layer similar to the above is formed on a conductive substrate, and then a charge generating layer containing the azo compound as a charge generating material is formed by means of coating or the like. Good. further,
The charge generation layer may be formed by dispersing a charge generation material and a charge transport material in a binder resin and applying the dispersion material.

As the charge-transporting material, conventionally known materials can be used, for example, oxadiazole compounds such as 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole. , Styryl compounds such as 9- (4-diethylaminostyryl) anthracene, carbazole compounds such as polyvinylcarbazole, pyrazoline compounds such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline, hydrazone compounds, triphenyl Nitrogen-containing cyclic compounds such as amine compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds, condensed polycyclic compounds can give.

These charge transport materials are used alone or in combination of two or more. When a charge transporting material having film-forming property such as polyvinylcarbazole is used,
The binder resin is not always necessary. Further, as the binder resin used in the above single-layer type or laminated type photoreceptor,
Various resins can be used, for example, styrene-based polymers, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, acrylic polymers, styrene-acrylic copolymers. , Polyethylene, ethylene vinyl acetate copolymer, chlorinated polyethylene, polyvinyl chloride, polypropylene, vinyl chloride-vinyl acetate copolymer, polyester, alkyd resin, polyamide, polyurethane, polycarbonate, polyarylate, polysulfone, diallylphthalate resin, ketone Resin, polyvinyl butyral resin, thermoplastic resin such as polyether resin, silicone resin, epoxy resin, phenol resin, urea resin, melamine resin, other crosslinkable thermosetting resin, epoxy acrylate, urethane-a Various polymers such as photocurable resins such relations and the like.

These binder resins may be used either individually or in combination of two or more. A solvent is used when the charge generation layer and the charge transport layer are formed by a coating method or the like. As this solvent, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol and butanol, aliphatic hydrocarbons such as n-hexane, octane and cyclohexane,
Benzene, toluene, aromatic hydrocarbons such as xylene, dichloromethane, dichloroethane, carbon tetrachloride, halogenated hydrocarbons such as chlorobenzene, dimethyl ether, diethyl ether, tetrahydrofuran, ethers such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, acetone, methyl ethyl ketone, Examples thereof include ketones such as cyclohexanone, esters such as ethyl acetate and methyl acetate, and various solvents such as dimethylformaldehyde, dimethylformamide and dimethylsulfoxide.

These solvents may be used either individually or in combination of two or more. In addition, in order to improve the sensitivity of the charge generating layer, known sensitizers such as terphenyl, halonaphthoquinones, and acenaphthylene may be used together with the charge generating material. Further, in order to improve the dispersibility of the charge transport material or the charge generating material, the dyeing property, etc., a surfactant, a leveling agent, etc. may be used.

As the conductive base material, various conductive materials can be used. For example, simple metals such as aluminum, copper, tin, platinum, gold, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass,
Examples thereof include a plastic material obtained by vapor deposition or laminating of the above metal, glass coated with aluminum iodide, tin oxide, indium oxide and the like.

The conductive base material may be in the form of a sheet or a drum, as long as the base material itself is conductive or the surface of the base material is conductive. As the base material, a base material having a sufficient mechanical strength when used is preferable. Each of the single-layer type and multi-layer type organic photosensitive layers may contain additives such as a sensitizer, a fluorene compound, an antioxidant, a deterioration inhibitor such as an ultraviolet absorber, and a plasticizer.

The amount of the charge transport material added to the single-layer type photosensitive layer is suitably 40 to 200 parts by weight, preferably 50 to 100 parts by weight, based on 100 parts by weight of the binder resin. Further, the addition amount of the charge transport material in the laminated charge transport layer is 10 to 100 parts by weight of the binder resin.
Suitably 500 parts by weight, preferably 25 to 200 parts by weight.

The amount of the charge generating material added to the single-layer type photosensitive layer is 0.1 to 50 parts by weight, preferably 0.5 to 30 parts by weight, based on 100 parts by weight of the binder. is there. Further, the addition amount of the charge generation material in the laminated charge generation layer is 5 to 5 parts by weight with respect to 100 parts by weight of the binder resin.
Appropriately is 00 parts by weight, preferably 10 to 300 parts by weight.

The thickness of the photosensitive layer formed is preferably about 5 to 100 μm, particularly about 10 to 50 μm in the case of a single layer type. On the other hand, in the case of a laminated type, the thickness of the charge generation layer is about 0.01 to 5 μm, preferably 0.1 to 5 μm.
About 3 μm, the thickness of the charge transport layer is about 2 to 100 μm,
It is preferably about 5 to 50 μm. Further, in the case of a single-layer type electrophotographic photosensitive member, between the base material and the photosensitive layer, and in the case of a laminated type electrophotographic photosensitive member, between the base material and the charge generation layer. A barrier layer may be formed between the base material and the charge transport layer and between the charge generation layer and the charge transport layer to the extent that the characteristics of the photoreceptor are not impaired. A layer may be formed.

When the charge generating layer and the charge transporting layer are formed by a coating method, the charge generating material and the binder resin may be formed by a known method such as roll mill, ball mill, attritor, paint shaker or ultrasonic wave. It may be prepared by dispersing and mixing using a disperser or the like, and applying and drying this by a known means. As described above, the charge generation layer may be formed by depositing the above charge generation material.

[0048]

The present invention will be described in detail below with reference to examples. Example 1 Using a bisazo compound represented by the following general formula (IV) as a charge generation material, single-layer type and multi-layer type photoreceptors were prepared by the following procedure.

[0049]

[Chemical 9]

(Production of Single Layer Type Photoreceptor) 8 weight of bisazo compound as charge generating material and 3,3'-dimethyl-N, N, N ', N'-tetrakis-4- as charge transporting material. Methylphenyl- (1,1'-biphenyl)-
100 parts by weight of 4,4'-diamine and 100 parts by weight of a polyester resin as a binder resin were mixed and dispersed together with a predetermined amount of tetrahydrofuran using an ultrasonic disperser to obtain a coating solution for a single-layer type photosensitive layer. Prepared.

This coating solution was prepared by applying a diameter of 80 mm and a length of 350 mm.
Drum type positive charging type electrophotographic photoconductor having a single-layer type photosensitive layer having a film thickness of 24 μm, which is applied on the surface of the aluminum base tube by a dipping method and then dried by heating at 100 ° C. for 30 minutes in a dark place. The body was made. (Production of Laminated Photoreceptor) 100 parts by weight of polyvinyl butyral as a binder resin, 100 parts by weight of a bisazo compound as a charge generating material, and a predetermined amount of tetrahydrofuran were charged in a ball mill and mixed with stirring for 24 hours, A charge generation layer coating solution was prepared.

This coating solution was prepared as follows: diameter 80 mm x length 350 mm
After being applied on the surface of the aluminum base tube by the dipping method, it was dried in a dark place with hot air at 110 ° C. for 30 minutes to be cured to form a charge generation layer having a thickness of 0.5 μm. Next, 100 parts by weight of polycarbonate as a binder resin and 3,3'-dimethyl-N as a charge transport material,
N, N ', N'-tetrakis-4-methylphenyl-
(1,1'-biphenyl) -4,4'-diamine 100
By weight and a predetermined amount of toluene were stirred and mixed with a homomixer to prepare a charge transport layer coating liquid.

This coating solution is applied onto the charge generation layer previously formed on the surface of the raw tube by the dipping method, and the temperature is maintained at 90 ° C. for 30 minutes.
A drum type negative charging type electrophotographic photoreceptor having a laminated type photosensitive layer was formed by forming a charge transport layer having a film thickness of about 20 μm by drying with hot air for a minute. Examples 2 to 7 As the charge generating material, A in the general formula (Ia) is represented by the above formula.
Single-layer type and multi-layer type photoconductors were prepared in the same manner as in Example 1 except that the bisazo compound, which is the coupler residue represented by (A2) to (A7), was used.

Comparative Examples 1 to 3 Single-layer type and laminated type photoreceptors were prepared in the same manner as in Example 1 except that the bisazo compounds represented by the following formulas (i) to (iii) were used. It was made. Comparative Example 1:

[0055]

[Chemical 10]

Comparative Example 2:

[0057]

[Chemical 11]

Comparative Example 3:

[0059]

[Chemical formula 12]

The following tests were conducted on the electrophotographic photosensitive members of the above-mentioned respective Examples and Comparative Examples to evaluate their characteristics. Measurement of Initial Surface Potential Each electrophotographic photosensitive member is loaded in an electrostatic copying tester (Gentec Cynthia 30M, trade name, manufactured by Gentech), and the surface thereof is positively or negatively charged to obtain an initial surface potential Vs. .p. (V) was measured.

Measurement of Half-Exposure Amount and Residual Potential The electrophotographic photosensitive member charged in the above-mentioned measurement of the initial surface potential was exposed to an exposure intensity of 10 lux by using a halogen lamp as an exposure light source of an electrostatic copying tester. Exposure under the conditions,
The half-exposure amount E1 / 2 (lux.sec) was calculated by obtaining the time until the surface potential became 1/2.

The surface potential at the time point 0.15 seconds after the start of the exposure is measured and the residual potential V1r.p. (V) is measured.
And Measurement of Light Stability The electrophotographic photosensitive member was loaded in an electrostatic copying machine (model number DC-111 manufactured by Mita Kogyo Co., Ltd.) to continuously copy 1000 sheets, and then repeatedly exposed in the same manner as above. After that, the residual potential V2r.p. (V) was measured. Then, the residual potential V
The difference ΔVr.p. (V) between 1r.p. and V2r.p. was obtained.

The above results are shown in Table 1.

[0064]

[Table 1]

From the results in Table 1 above, the electrophotographic photosensitive members of Examples 1 to 7 having the constitution of the present invention, in both the single-layer type and the laminated type, had an initial surface potential Vs. p. is high, the residual potential V1r.p. is lower than in Comparative Examples 1 to 3, and the half-exposure amount E1 / 2 is smaller than that in Comparative Examples 1 to 3, so that the sensitivity characteristics are excellent. I knew it was. In addition, in Examples 1 to 7 described above, ΔVr.
Since the p. was small, it was found that each of them had excellent durability.

[0066]

INDUSTRIAL APPLICABILITY As described above, the electrophotographic photoreceptor of the present invention is provided with a photosensitive layer containing a specific azo compound having high sensitivity and photostability, and therefore has high sensitivity and It has excellent durability.

Claims (1)

[Claims] 1. A photoconductor comprising a conductive layer and a photosensitive layer containing an azo compound represented by the following general formula (I). [Chemical 1] [In the formula, A represents a coupler residue]